Shoei CWR-F2 Transition Photochromic Visor for NXR2 HelmetsShoei CWR F2 Photochromatic Visor Transitions Photochromic technology allows visors to automatically and seamlessly change from clear to dark in sunlight. The process works when photochromic dyes embedded into the lens or shield react to UV light, changing levels of darkness with the sun. When UV light is removed, a chemical reaction driven by ambient heat reconverts the activated photochromic molecules to their original, clear form and the lens